Giannis vs Polinik on the color of bronze :)

[Paullus Scipio]

It gets more confusing. I just checked a book on metallurgy. It states that
1. brass under 20% zinc normally has a brownish-reddish colour.
2. bronze under 20% tin normally has a brownish-reddish colour.

only when the proportion of copper goes below 80% the red / copper turns into a yellow tone, on both metals.
I cannot verify this empirically, since I never made alloys with over 10% tin, zink or lead, but all the ones I made were rather reddish / coppery when cast and cleaned.

However, I see no reason to question metallurgical tables, I assume those statements are correct. To me it perfectly makes sense in regard of my experience in mixing Roman alloys.

A look at the two sites posted by Greg - Jeroen's and Neil's would seem to provide empirical evidence that 'ancient bronze' of around 10% tin is a decided gold/yellow colour ( which may have a rosy tint under certain lighting conditions). I also attach an actual example of a bronze sword found - which again is 'gold/yellow' coloured. The statements you have quoted would seem to be plainly wrong, since brass and bronze around 10% tin or zinc are 'gold/yellow' when new and polished - certainly not brownish-reddish! One need only look at Jeroen's and Neil's re-creations to see that. ( My father used to make brass artifacts when I was a boy, and used several types of brass, and coppery modern bronze, but I never saw anything a 'brownish-reddish' colour). Are those statements made in a different context perhaps??

What does this mean, then? As far as we can see from the Haltern finds, where we have a metallurgical analysis for (I think) all items, only a small amount was actually in a yellowish tone. The question is, in the end: Weren´t many / most of these items tinned anyway?
I don't believe you can extend a single find on a Roman site to cover Greek equipment of a different time period. Certainly only a small minority of helmets found show signs of 'tinning' - designed to give a 'silver' impression, and as Jeroen points out, one reason for using 'yellow' bronze is to give a 'gold' impression

And, following: Would a tinned surface on a helmet like the one from Sicily result in a yellowish colour nowadays? Hmmmm...
I'm afraid the tinned surface generally looks quite different due to the different oxidation, and because of wear patterns - see attached photos of a tinned Chalcidian helmet - note the bronze appears 'yellow/gold', with the remains of the tinning showing as dark patches - I've included one taken under a 'warm' light as well, so as to show how the bronze looks 'rosy' or warm under different lighting !! The photographer used a reddish light because everyone knows bronze is supposed to be reddish, :roll: but in the more natural lighting conditions of the other two photos, the truer 'yellow/gold' colour is visible.......

Besides:
In regard of low copper part in alloys, I think you forgot the mirror-bronzes in Antiquity, Paul. I just thought of them, and IIRC these often have below 70% copper.
Yes, quite right......if we are going to extend the scope of ancient bronze beyond Greek armour, perhaps one should note the many bronze objects from Chinese tombs, many untarnished, of 5-15% tin content - which again are predominately 'yellow/gold' coloured......

See
Friedrich Tabellenbuch – Metall- und Maschinentechnik, (Troisdorf 2008).
C. J. B. Karsten, System der Metallurgie: geschichtlich, statistisch, theoretisch und technisch (Berlin 1831).